Regarding applications for use of so called plastic pipe drilling typically e.g. well drilling or e.g. forepoling come into question. An advantage of use of a plastic pipe in drilling is first of all the fact that plastic pipes are very light compared to steel pipes, thanks to which they also have more profitable transport costs and they are easier to handle at a construction site. Furthermore a plastic pipe is significantly cheaper than a corresponding steel pipe. A plastic pipe does not frost for that matter and when being mounted into the ground, it does not break the bits of crushers or drills, when the soil is later on being e.g. worked or drilled. Furthermore in caves or quarries, metal may not blend with broken rocks, which is why use of plastic pipes in drilling has a very remarkable meaning in that context as well.
Today significant problems are, however, related to plastic pipe drilling, which is why it is not possible to exploit the same to the extent that there is a need for or that there are possibilities in practice. This is among other things due to the fact that the present arrangements require first of all use of a steel pipe in the beginning of drilling, whereby it is only after that possible to start using in the drilling a plastic pipe to be coupled with the steel pipe e.g. by a screw joint and after that further plastic pipes to be coupled with each other one after the other. On the other hand solutions are being used, which are based on a screw joint coupling between a plastic pipe with a readymade threading and a casing shoe.
The former solution is not satisfactory first of all due to the fact that there is still a need for use of a steel pipe in the starting phase, whereby it is possible to exploit plastic pipes with preworked threadings only after the above phase. Use of plastic pipes with readymade threadings has, however, found out to be very difficult in practice, because a threaded part of a plastic pipe being coupled with a casing shoe made of steel easily gets cut due to differences in shapes of mutual threadings in the parts in question. The problems related to preworked threadings in plastic pipes are probably due to the differences of steel and plastic e.g. because of strength and thermal expansion characteristics thereof and the like reasons.
There have been efforts for exploitation of joint arrangements in plastic pipes with readymade threadings on the other hand by using a very long coupling stem in the casing shoe with necessary elasticity means, such as damping O-rings, despite of which a screw joint between a casing shoe and a plastic pipe to be carried out with reasonable costs has not been managed to accomplish so far. All the types of arrangements described above require rather massive arrangements in order to make sure a screw joint between the casing shoe and the plastic pipe, which is why they increase the manufacturing costs disproportionately and make use of the solutions in question significantly more difficult in installation work in practice.